The primary objective of the proposed study is to provide a data base of detailed and quantified behavioral observations pertinent to the hypothesis that neural development is responsive to and normally dependent upon functional activity during embryonic and larval (fetal) stages. Although behavioral and neural development have been clearly demonstrated to depend upon the amount and characteristics of experience and neural function during early postnatal stages, similar data concerning functional effects during the earliest stages of neuro-behavioral development are lacking. Due to this deficiency of experimental data, the developmental role of such a common phenomenon as spontaneous embryonic motility, reflecting intrinsic neural activity, is uncertain. The proposed methodology involves anesthetizing amphibian embryos prior to onset of embryonic motility, followed by their release from the anesthetizing agent after various intervals of immobilization. Quantification of motor behaviors and sensory-motor responses of these animals will be carried out at defined intervals after release. Identical measures will be made on normal and control animals. Investigation of other neurobiological aspects of development will be performed as indicated by the behavioral results.